Gravity Driven Pile Tower Based Device For Pipeline Lifting And Support And Method Of Use

ABSTRACT

A system and method for securely cradling a subsea pipeline is claimed that lands on one side of the pipeline, is embedded into the sea floor, reaches under the pipeline, positions the cradling structure, and then lifts the pipeline. The system typically comprises a gravity driven pile based device, comprising a pile tower, a roller carriage assembly, and a jacking assembly that engages the roller carriage assembly and pile tower rails.

FIELD OF THE INVENTION

The disclosed inventions relate to a tool for securely cradling a subseapipeline. More specifically, the disclosed inventions relate to a toolfor securely cradling a subsea pipeline which land on one side of thepipeline and embed into the sea floor near the pipeline.

BACKGROUND

Subsea pipelines need to be elevated with respect to the sea floorproximate the pipeline on occasion for numerous reasons. It is oftenadvantageous for such a tool to be capable of securely cradling thepipeline.

DRAWINGS

The various drawings supplied herein describe and are representative ofexemplary embodiments of the invention and are described as follows:

FIG. 1 is a view in partial perspective of an exemplary embodiment ofthe device, and FIG. 1A is a view in partial perspective of a detail ofthe device;

FIG. 2 is a view in partial perspective of an exemplary embodiment ofthe roller arm assembly, and FIGS. 2A-2B are views in partialperspective of details of the exemplary embodiment of the roller armassembly;

FIG. 3 is a top-down view in partial perspective of an exemplaryembodiment of the roller assembly;

FIG. 4 is a top-down view in partial perspective of an exemplaryembodiment of the roller assembly, and FIGS. 4A-4F are views in partialperspective of details of the exemplary embodiment of the rollerassembly;

FIG. 5 is a view in partial perspective of an exemplary embodiment ofthe jacking assembly, and FIGS. 5A-5G are views in partial perspectiveof details of the exemplary embodiment of the device;

FIG. 6 is a view in partial perspective of an installed deployment of anexemplary embodiment of the device;

FIG. 7 is a view in partial perspective of a device embedded in the seafloor with the roller arm assembly extended underneath a pipeline in anexemplary embodiment of the device;

FIG. 8 is a view in partial perspective of a device embedded in the seafloor with the roller arm assembly extended underneath a pipeline andthe cylinder extended in an exemplary embodiment of the device;

FIG. 9 is a view in partial perspective of a device embedded in the seafloor with the roller arm assembly engaged with and supporting thepipeline in an exemplary embodiment of the device; and

FIG. 10 is a view in partial perspective of a device embedded in the seafloor with the cylinder and lead screw assemblies removed in anexemplary embodiment of the device.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring generally to FIGS. 1 and 6, in general, in various embodimentsdevice 1 is a tool that lands on one side of a pipeline, e.g. pipeline100 (FIG. 6), and embeds into the sea floor, usually using gravity.Device 1 comprises components that reach under pipeline 100 in order toposition a cradling component of device 1. Device 1 provides a length ofvertical adjustability for pipeline 100 and supports a load applied bythe weight of pipeline 100. The cradle must provide sufficient surfacearea to avoid excessive stress concentration on pipeline 100. Inpreferred embodiments, the main structure of device 1 is fabricated outof 16″ OD, 1″ wall thickness riser pipe. In various embodiments, device1 is capable of being sent overboard from a vessel in a horizontalposition and deployed subsea in a vertical position.

In general, device 1 comprises three major subassemblies: pile tower 10,roller carriage assembly 30, and jacking assembly 70.

Pile tower 10 is the main structural component of device 1. In typicalconfigurations it comprises three equally spaced legs 15. In anembodiment, legs 15 are 16″ OD riser pipes around 57 feet in length.Preferably, legs 15 comprise API X70 steel with the ends, other thanI-beams 111 (FIG. 2A) and cylinder mounting slots 112 (FIG. 5A), made ofASTM A36 steel. I-beams 111, rails 3 (FIG. 5E), and cylinder mountingslots 112 are typically made from grade 70 steel.

The top of pile tower 10 is typically tied together with three gussetswhich are themselves tied to a short section of middle pipe which israised above the level of legs 15. A three inch thick pad-eye mayprotrude from the middle pipe and allow for a vertical deployment ofpile tower 10.

Skirt 20 comprises one or more skirts 22 connected to the bottom of legs15. Skirt 20 also provides a bearing surface for embedment into seabed110 (FIG. 6). In a preferred embodiment, skirt 20 comprises three skirts22, each of which measures around 1″ thick by around 55″ wide by around300″ tall. Skirts 22 each have one or more holes to vent seawater duringembedment, typically two holes having around a 12″ diameter. Scale 21may be present to measure a level of embedment, e.g. starting at 5 feetabove a mud line. In typical embodiments, skirts 22 are stitch welded tolegs 15.

In some embodiments, a small mud mat 21 provides surface area forresistance during embedment. Mud mat 21 typically sits above skirt 20and extends out past legs 15. Mud mat 21 has vent holes and, in certainembodiments, provides around at least 4250 square inches of surfacearea. In certain embodiments, one or more anodes are welded to the topof mud mat 21 to provide cathodic protection, e.g. ten twenty-nine poundanodes 27.

One or more rails 14, which in a preferred embodiment comprise geartooth rails, are disposed along the outside of at least two legs 15 ofpile tower 10 to provide one part of a ratcheting mechanism. Rails 14are typically around two-inches wide and extend from mud mat 21 up tothe top of pile tower 10. One of legs 15 may comprise scale 11 which maybe painted on an outer surface of leg 15. Scale 11 may vary according tothe desired height of pile tower 10 and usually measures an elevationabove mud mat 21.

The top of pile tower 10, e.g. landing funnel 80, may be angled towardthe center to provide a landing “funnel” for a weighted follower.

Lifting bail 2 (FIG. 1A) may also be present, attached to the bottom ofpile tower 10, to facilitate horizontal lifting and overboardingoperations.

In some embodiments, pile tower 10 is coated in three coat epoxy, exceptfor a portion of pile tower 10 below a certain foot mark on 21, which isleft uncoated.

Roller carriage assembly 30 is the component that physically contactspipeline 100 (FIG. 6). Roller carriage assembly 30 comprises three majorsubassemblies: carriage weldment 40, lead screw drive assembly 60, androller arm assembly 50.

Carriage weldment 40 is a load-bearing part and typically comprisesthree or more plates 31, which are preferably 18″ ID rolled plates,which are tied together with top plate 34 and bottom plate 35. Tworolled plates 31 comprise slots and channels 36 on their respectivesides to allow rails 14 to pass through rolled plates 31. Rails 3 (FIG.5E) mounted to bottom plate 35 secure a sliding roller frame 54 tocarriage weldment 40.

Latch mount plates 4 (FIG. 5A) on top of each channel 36 act as mountingpoints for latches 33. A smaller hole 113 (FIG. 5 b) on each of latchmount plates 4 allows for a lockout pin (not shown in the figures) to beinstalled which overrides the ratcheting mechanism.

Two slotted cylinder plates 112 (FIG. 5A) are mounted on top of carriageweldment 40. Cylinder 114 (FIG. 5) slides into slots 115 (FIG. 5D) inslotted cylinder plates 112.

Lead screw drive assembly 60 typically comprises a hydraulically poweredunit, e.g. motor 63, that drives roller arm assembly 50 back and forthalong an axis defined by roller frame 54. In preferred embodiments, leadscrew drive assembly 60 is able to be removed subsea to extend its life.Motor 63 is preferably a 240 cc hydraulic motor which is coupled to leadscrew 61 which can vary in length as needed, e.g. from around 1.5 inchesto around 5 inches, with a typical travel of around 59 inches.

Motor mounting frame 6 (FIG. 4B) houses a docking probe receptacle, 17Hdual port manifold 7 (FIG. 5G), and motor 63. The docking probereceptacle interfaces with the docking probe on the carriage. Lead screw61 nut is flanged and is attached to a drive plate. The drive plateinterfaces with slots on the roller frame in order to drive it back andforth. Two stainless rods running the length of the screw prevent thedrive plate from rotating while the screw is rotating. The 17H manifoldprovides an ROV interface for driving roller arm assembly 50.

Roller arm assembly 50 slides in and out of carriage weldment 40 onroller frame 54. Lead screw drive assembly 60 is removable andinterfaces with carriage weldment 40 and roller arm assembly 50 in orderto drive roller arm assembly 50 forward and backward with respect anaxis defined by carriage weldment 40. Latches on the sides of carriageweldment 40 interface with the gear rack in order to perform a one-wayratcheting function. Two ROV operable pins on top of carriage weldment40 allow for the cylinder to be removed subsea. One 725 pound anode iswelded to the top of carriage weldment 40 and provides cathodicprotection for the carriage, as well as pile tower 10. UHMW strips linethe inside of each of the three rolled plates of the carriage. Thisreduces friction and eliminates the possibility of carriage weldment 40binding up while being lifted under load.

A set of rollers 52 is mounted to roller frame 54, which typicallycomprises a set of cantilevered I-beams, and roller frame 54 istypically mounted to carriage weldment 40 to support pipeline 100. Ahydraulic motor and lead screw are used to drive the I-Beams back andforth. Latch pawls interface with the gear teeth on pile tower 10 toperform a one-way ratcheting action.

Roller box assembly 50 defines a pipeline interface and allows for freeaxial movement of pipeline 100 (FIG. 6) due to expansion via threerollers 52, 53. Roller arm assembly 50 comprises roller frame 54,typically a set of matching I-beams, slotted drive mount 9 (FIG. 4C),and roller box assembly 59.

In embodiments, roller frame uses a set of I-beams that ride along rails3 (FIG. 5E) in carriage assembly 40.

Drive mount 9 is typically bolted to the back of roller frame 54 andaccepts drive plate 116 (FIG. 4A) on lead screw drive assembly 60.Machined plate 117 (FIG. 4D) rides on top of roller frame 54 and housesthe bearing and hub for roller box assembly 59.

Roller box assembly 59 contains typically contains two or more rollers52, 53, preferably three rollers 52, 53 as well as mounting plates 118(FIG. 4D), hub 119 (FIG. 4E) (which can be a pivoting base), andbearings 120 (FIG. 4F). Two outside rollers 52 match the radius ofpipeline 100 (FIG. 6) and extend up to three inches below the centerlineof pipeline 100. Middle roller 53 matches the radius of pipeline 100 butdoes not extend up the side of pipeline 100. Rollers 52, 53 aretypically disposed about stainless steel axles (not specifically shownin the figures). Rollers 52, 53 are held together with two mount plates118 (FIG. 4D), which preferably comprise bronze bushings for bearings.

A pivoting base 119 (FIG. 4E) of roller box assembly 50 allows rollers52 to dynamically conform (pitch) to the actual pipeline 100 position,thus ensuring an equal distribution of weight on all three rollers 52,53 at all times.

The hub weldment supports the rollers 52 and has a bronze bearing cuparound it to reduce friction. Roller box assembly can usually pivot upand down, as well as yaw side-to-side, but cannot roll side-to-side.

The roller shafts and hub typically comprise 316 stainless steel. Thesurfaces of rollers 52, 53 typically comprise 90 durometer polyurethane.

Jacking assembly 70 comprises jacking frame 77, latches 72, two ROVoperable pins 74, and two anodes 121 (FIG. 5F) and is used to raiseroller carriage assembly 30. Its “inchworm” hydraulic lifting mechanismis typically completely removable and comprises a hydraulic liftingmechanism and lateral adjustment hydraulic motor-driven screw-drivemechanism which allows for removal for ease of repairs andpreservation/storage for future deployment/adjustments as required.

Jacking frame 77 comprises two rolled plates 71, which act as interfacesfor rails 14, connected by I-beam 78. Rolled plates 71 slide up and downalong rails 14. Channels 79 in the sides of rolled plates 71 allowclearance for rails 14 on pile tower 10. Holes 79 a in each channel 79allow for lockout pins (not shown in the figures) to be installed inorder to set the location of jacking frame 77 relative to legs 15.

Mounting plates (not shown in the figures) may be used for mountingone-way latches 72. The mounting plates may also comprise a smallersecondary hole (not shown in the figures) which can be used to unlockand override the one-way ratcheting feature.

Two slotted plates 112 (FIG. 5A) on the bottom side of I-beam 79 providea mounting location for cylinder 114 (FIG. 5).

Jacking frame 77 also comprises two threaded bosses on the front inorder for a continuity pin (not shown in the figures) to be installed.

Two 725 pound anodes 121 (FIG. 5F) are attached to the back of jackingframe 77 to provide cathodic protection for jacking frame 77 and piletower 10.

Jacking frame 77 typically uses the same one-way latch pawls 72 as doesroller carriage assembly 30.

Cylinder assembly 121 (FIG. 5F) is used to alternately raise jackingframe 77 and roller carriage assembly 30. ROV operable pins allow forremoval of cylinder 114 (FIG. 5). Cylinder assembly 122 (FIG. 5G)consists of cylinder 114 and hydraulic control panel 123 (FIG. 5G).Cylinder 114 typically has a bore of around 5 inches and with 2 feet oftotal stroke. In preferred embodiments, cylinder 114 is rated for up to55,000 pounds of force when extending and 45,000 pounds when retracting.

Cylinder 114 (FIG. 5) is typically fitted with trunion nuts 124 (FIG.5G) to allow it to be installed and removed from slotted plates 112(FIG. 5A) on carriage weldment 40 and jacking frames 77. Hydrauliccontrol panel houses a 17H dual port manifold, as well as a 5000 psipressure gauge. The gauge can be used to roughly estimate the weight ofthe load being lifted. The 17H manifold allows for ROV control of thecylinder.

In preferred embodiments, rotating components comprise 45 ksi nickelaluminum bronze; pins, rotating shafts, or areas where corrosionresistance is important comprise 316 stainless steel; and rolled plateswhich ride up and down legs 15 comprise ultra high molecular weightpolyethylene (“UHMW”).

In the operation of various embodiments, referring additionally to FIGS.6-9, after device 1 is embedded into sea floor 110, an ROV will actuatemotor 63 which will turn lead screw 61, thus extending roller boxassembly 59 until rollers 52,53 are directly under pipeline 100. The ROVwill then swivel roller box assembly 59 until roller box assembly 59 isaxially aligned with pipeline 100. The ROV will then actuate cylinder114 (FIG. 5) in order to extend it and thereby extend cylinder 114.One-way latches 33 on carriage weldment 40 will keep carriage weldment40 from moving down, while one-way latches 72 on jacking frame 77 allowjacking frame 77 to move upward. Once the cylinder is fully extended,the ROV will then retract the cylinder. The cylinder will retract. Theone-way latches will keep jacking frame 77 from moving down, while theone-way latches on carriage weldment 40 will allow carriage weldment 40to be pulled up by the cylinder. This process is repeated until pipeline100 is at the desired height. The ROV will then install pins in carriageweldment 40 and jacking frame 77 to fix its position. The ROV willinstall continuity pins in the 5 threaded bosses on carriage weldment 40and jacking frame 77. The ROV will then remove cylinder assembly 122(FIG. 5G) as well as lead screw drive assembly 60.

During lifting operations, pile tower 10 will be lifted by a two-partsling via a padeye at the top of pile tower 10, and a lifting bail atthe bottom of pile tower 10. A 60° sling angle will be used whenlifting. This will result in roughly 35,000 pounds of force on eachlifting eye. During transport, pile tower 10 will be laid on deckhorizontally. Device 1 will lay with its pipeline-facing side facingdown on the deck. Timbers or other blocks will be laid under pile tower10 to raise the structure slightly off of the deck. The 60,000 poundweight of device 1 will rest on these timbers.

It will be understood that various changes in the details, materials,and arrangements of the parts which have been described and illustratedabove in order to explain the nature of this invention may be made bythose skilled in the art without departing from the principle and scopeof the invention as recited in the appended claims.

What is claimed is:
 1. A gravity driven pile based device, comprising:a. a pile tower, comprising: i. a plurality of legs arrangedsubstantially parallel to each other to define an interior comprising aninterior longitudinal central axis; and ii. a predetermined number ofrails disposed about an outside of a plurality of the legs, the railscomprising outwardly exposed teeth; iii. a skirt dimensioned and adaptedto be disposed between a predetermined portion of the plurality of legsand to further provide a bearing surface for embedment into soil; b. aroller carriage assembly dimensioned and adapted to engage the rails,the roller carriage assembly further comprising: i. a carriage weldment;ii. a lead screw drive assembly; and iii. a roller arm assembly; and c.a jacking assembly dimensioned and adapted to engage the roller carriageassembly and the rails, the jacking assembly comprising a jacking frame.2. The gravity driven pile based device of claim 1, wherein: a. theplurality of legs comprises three legs; and b. the predetermined numberof rails comprises two rails disposed about an outside of two of thethree legs.
 3. The gravity driven pile based device of claim 1, furthercomprising latch pawls connected to the carriage weldment and thejacking frame, the latch pawls dimensioned and adapted to interface withthe outwardly exposed teeth to perform a one-way ratcheting action. 4.The gravity driven pile based device of claim 1, wherein the skirtcomprises a plurality of skirt panels, each skirt panel dimensioned andadapted to substantially extend along an outer portion of two of theplurality of legs.
 5. The gravity driven pile based device of claim 1,further comprising a mud mat disposed proximate the skirt anddimensioned to extend a predetermined distance past an outer surface ofthe legs.
 6. The gravity driven pile based device of claim 5, whereinthe mud mat further comprises a predetermined number of anodesdimensioned and adapted to provide cathodic protection.
 7. The gravitydriven pile based device of claim 5, wherein the rails are disposedalong an outside of the legs and extend from proximate the mud mat toproximate an end of the legs distal from the mud mat.
 8. The gravitydriven pile based device of claim 1, wherein the carriage assemblyfurther comprises: a. an upper plate; b. a lower plate; c. a selectivelyremovable cylinder; d. a first plurality of cylinder plates comprising aslot and a channel on the sides dimensioned and adapted to slidinglyreceive the cylinder; e. a second plurality of latch rolled plates ontop of each channel dimensioned and adapted to act as mounting pointsfor a corresponding number of latches, the latches comprising a smallerhole on each of the latch mount plates allows for a lockout pin to beinstalled which overrides a ratcheting mechanism; and f. a plurality ofthreaded bosses, one on the back of the rear rolled plate and one oneach side of the roller frame box, dimensioned and adapted to receive afastener therethrough to create continuity with the roller frame andlegs and provide cathodic protection.
 9. The gravity driven pile baseddevice of claim 1, wherein the lead screw drive assembly furthercomprises a plurality of rods running the length of the screwdimensioned and adapted to prevent the drive plate from rotating whilethe screw is rotating.
 10. The gravity driven pile based device of claim1, wherein the lead screw drive assembly comprises a hydraulicallypowered motor assembly dimensioned and adapted to drive the rollerassembly back and forth along its rails.
 11. The gravity driven pilebased device of claim 10, wherein the hydraulically powered motorassembly further comprises: a. a motor mounting frame; b. a dockingprobe receptacle housed within the motor mounting frame, the dockingprobe receptacle dimensioned and adapted to interface with a dockingprobe connected to the carriage assembly; c. a dual port manifolddimensioned and adapted to provide an ROV interface for driving theroller assembly; and d. a hydraulic motor housed within the motormounting frame and operatively coupled to the lead screw.
 12. Thegravity driven pile based device of claim 1, wherein the roller assemblyfurther comprises: a. a roller frame dimensioned and adapted to supporta load of the pipeline, the roller frame further dimensioned and adaptedto be slidingly engaged to the carriage assembly; b. a drive mountattached to the roller frame and dimensioned and adapted to accept aportion of the lead screw assembly; and c. a roller box assembly,comprising: i. a plurality of rollers dimensioned and adapted to conformto the pipeline; ii. a plurality of mounting plates; iii. a hub, and iv.a plurality of bearings.
 13. The gravity driven pile based device ofclaim 12, wherein a predetermined number of the plurality of rollers aredimensioned and adapted to match a radius of the pipeline and extend afurther predetermined distance below a centerline of the pipe.
 14. Thegravity driven pile based device of claim 13, wherein: a. thepredetermined number of the plurality of rollers is two; and b. a thirdroller of the plurality of rollers is dimensioned and adapted to match aradius of the pipeline but which is further dimensioned and adapted tonot extend up the side of the pipeline.
 15. The gravity driven pilebased device of claim 1, wherein the lead screw drive assembly isremovable and interfaces with the carriage weldment and roller assemblyin order to drive the frame along the predetermined direction.
 16. Thegravity driven pile based device of claim 1, wherein the jacking frameassembly further comprises: a. a jacking frame comprising a plurality ofrail interfaces dimensioned and adapted to slidingly receive the rails,the rail interfaces comprising channels, the channels comprising portsdimensioned and adapted to allow for lockout pins to be installed inorder to set the location of the jacking frame with respect to the piletower; b. a ratcheting assembly comprising a plurality of latchesattached to the rail interfaces, the latches dimensioned and adapted toselectively engage the rails; c. a plurality of ROV operable pins; andd. a plurality of anodes.
 17. The gravity driven pile based device ofclaim 16, wherein the latches on the sides of the carriage assemblyinterface with the rails in order to perform a one-way ratchetingfunction.
 18. The gravity driven pile based device of claim 16, whereinthe jacking frame further comprises a cover plate disposed about a topportion of the rail interfaces, the cover plate dimensioned and adaptedfor mounting the ratcheting assembly, the cover plate further comprisinga smaller secondary port dimensioned and adapted to unlock and overridethe one-way ratcheting feature.
 19. The gravity driven pile based deviceof claim 1, further comprising an angled landing funnel dimensioned andadapted to accept a weighted follower, the angled landing funneldisposed at a top portion of the pile tower within a portion of theinterior.
 20. The gravity driven pile based device of claim 1, furthercomprising a lifting bail attached to a bottom portion of the piletower, the lifting bail dimensioned and adapted to facilitate ahorizontal lifting and overboarding operation of the gravity driven pilebased device.